His liberty may be gone, but billionaire criminal Thomas Kwok Ping-kwong is still sporting his distinctive haircut after arriving at Stanley Prison to serve his five-year sentence for graft - despite prison rules against longer hair. In a picture taken this morning, and despite reports that he had been given a haircut, Kwok could be seen with his distinctive over-the-ear hairstyle as he walked through the prison grounds, watched by other prisoners. The sight of Kwok with his hair still covering his ears has sparked speculation about the treatment of the former Sun Hung Kai Properties co-chairman and three others sentenced last week in the city's highest-profile graft trial. The Correctional Services Department insists all male prisoners have their hair cut above their ears - a rule that was the subject of a legal challenge from a lawmaker earlier this year. In a statement yesterday that did not mention any specific prisoner, a department spokesman said: "Except provided with justifiable reason like religious or health considerations, a male person in custody has to cut his hair according to the directions." The spokesman said that the department would not allow exemptions on the basis of personal preference or the image of an individual in custody. During his trial, the Court of First Instance heard that Kwok suffered from a birth defect that left him with no ear canal and he needed to wear hearing aids. Other high-profile figures involved in the case, including former top government official Rafael Hui Si-yan, 66, appeared to have their hair shorter than during the trial. Hui was sentenced to 7½ years. Also convicted following the marathon corruption trial that shed light on collusion between the city's business and political elites, were Kwok aide Thomas Chan Kui-yuen, 68, and former stock exchange official Francis Kwan Hung-sang, 64. Kwok's brother and co-chairman, Raymond Kwok Ping-luen, was cleared. All four of those convicted were moved to Stanley on Saturday after spending their first week in custody at Lai Chi Kok Reception Centre. In September, lawmaker "Long Hair" Leung Kwok-hung filed a writ in the High Court against the Correctional Services Department for cutting his signature locks when he was jailed in June. Leung said the rule requiring male prisoners to have their hair cut short was discriminatory because women did not have to undergo a haircut, and breached his rights.